Page:Popular Science Monthly Volume 89.djvu/537

��THE way aoroplanes were ildwii before the war seems almost ridiculous now, after men have

really learned how to fly as the result of

war's exigencies.

them an eas^- pre}

and for attack- ing machines.

When it be- came necessary

to dart out of

the range of a

high-angle bat- tery, which

had suddenK-

revealed its

presence with

bursting shrap- nel, or when

only a C|uick

mane u \- e r

could prevent

a hostile

machine from

blocking the

wa>' home, the

old- fashioned,

steady, level flyer and slow

climber

.proved a very death- trap. Looping-the- loop, caper-cutting, all the acrobatic performances that attend exhibition flying l)ecame normal exolutions. Only excess power for a sudden burst of speed and climbing would avail in a perilous moment.

A fast-climbing machine, which also has the virtue of exhibiting great lifting power in the thin air of high akiludes, naturally vaults into the air easily in a difliculi start on rough ground. In a critical landing —when, for instance, the groimd, whicli, from above seems in\it- ingly sniootli, turns out to be alarmingly rough — the fast-climbing machine can easily stop its swift descent and leap lightly over an obstacle. By reducing his power while the machine is flying at

A machine thus able to deal with rough ground is most stable in rough air. An

aviator fears what he calls a "hole in the air" — a pocket formed by a downwardly- twisting cur- rent. Into such a hole he drops in a sickening way because his wings no longer have an upward blast to support them. He saves himself, not by trying to climb out — a useless proceeding — ■ but by steering d oiv n -w a r d , thus increasing his speed and likewise the pressure be- ji e a t h his wings. "To go up, one must sometimes steer up, at other times steer down," Wilbur Wright told me in his little insignificant bicycle shop in Dayton, Ohio, in 1905, in discussing the low- powered Wright machine.

Evidently the aviator needed power to combat these dilficulties. This he obtained by resorting to surplus-powered and reserve-powered machines. There would seem to be no distinction between the two terms, but the ditTerence is this: the surplus-powered machine has a motor which is more than able to make it fly and the excess power of which is constantly used for normal flight; the reser\-e-powered machine uses its excess <)ni\' in an emergency.